Study On Electrical Conductivity Of Lithium Niobate

Lithium Niobate (LiNbO₃:LN for short) is one of the very important multifunctional crystals, excellent thermal stability, chemical stability and mechanical stability. It possesses excellent piezoelectricity, nonlinear-optics, electro-optics, and photo-refractive characters. After that, most researches were carried on LiNbO₃ crystal. People are interested in its grown token and applications. Because of its multi-properties, it has being widely applied in nonlinear-optics, optical waveguides, optical switches and optical storage domain.The doped crystal has greatly improved performance, provides a broad application prospect.The study focused on the current domestic-doped lithium niobate crystal. Pure lithium niobate is the base of doped crystal. Intrinsic defects and extrinsic defects in the crystal affect the carrier mobility and complex. Expecially the dark conductivity of the crystal is effected by electron transfer which comes from intrinsic defects. In this article, we experiment with diffetent [Li]/[Nb]of pure lithium niobate ctyatal research, analysis of different [Li]/[Nb] of pure lithium niobate crystal dark conductivity effects,and establish the corresponding electron transfer model, provide a theoretical basis for doped crystal. In this article, based on lithium vacancy,we study dark conductivity of pure lithium niobate crystals with different [Li]/[Nb]. The main work includes:1. The crystal structure of LiNbO₃ crystal and the basic nature of the analyze,and clear pure LiNbO₃ crystal lattice structure of the basic nature.2. Comparatively analyses various disfigurement model of LiNbO₃ crystal, and chooses Li vacancy model as the base of this study. Analysis of the defect energy levels of ions in the crystal structure. In this article more attention are paid to dark conductivity.3. The three kinds of pure lithium miobate ctystal samples were measured by the method of external electric fields method. We obtained the the variation of conductivity with temperture. With that, analyze the possible reasons for this difference. Fitting the data, we obtained activation energy of crystals at different temperture..4. Combine the experimental results and theory analyses, we find that the difference reasons are related to the [Li]/[Nb] ratio. Finally concluded that:in the pure lithium niobate crystals, the concentration of electron and small polaron is an important factor affecting the electrical conductivity, electronic transport through small polaron is the primary mechanism for electrical conductivity.